From: Randy Dunlap <rdunlap@xenotime.net>
To: Onkar N Mahajan <kernzap@gmail.com>
Cc: linux-pci@vger.kernel.org
Subject: Re: pci_check_type2() help.
Date: Mon, 16 Apr 2012 12:13:08 -0700 [thread overview]
Message-ID: <4F8C6F44.6060407@xenotime.net> (raw)
In-Reply-To: <1334592160.26350.13.camel@oc4748611672.ibm.com>
On 04/16/2012 09:02 AM, Onkar N Mahajan wrote:
> Hello list,
>
> I am trying to understand the PCI functionality in Linux kernel.
> What is the best way to start to understanding this - where to start
> in the kernel code ? Books ? Manuals ?
>
> I started reading the code - where I am stuck in this function -
> pci_check_type2() ; Wherein I am not able to get from where these values
> 0xCFB,0xCF8,0xCFA are arrived at ? I guess these are port numbers , but
> in which manuals can I find this all information.
>
> linux/arch/x86/pci/init.c:
> static int __init pci_check_type2(void)
> {
> unsigned long flags;
> int works = 0;
>
> local_irq_save(flags);
>
> outb(0x00, 0xCFB);
> outb(0x00, 0xCF8);
> outb(0x00, 0xCFA);
> if (inb(0xCF8) == 0x00 && inb(0xCFA) == 0x00 &&
> pci_sanity_check(&pci_direct_conf2)) {
> works = 1;
> }
>
> local_irq_restore(flags);
>
> return works;
> }
>
>
> Please help me figuring out right manuals for this.
The PCI spec (version 2.1 seems to be all I have available)
discusses PCI Configuration Mechanisms and Special Cycles and
these PCI config registers.
--
~Randy
next prev parent reply other threads:[~2012-04-16 16:13 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-16 16:02 pci_check_type2() help Onkar N Mahajan
2012-04-16 19:13 ` Randy Dunlap [this message]
2012-04-16 16:20 ` Onkar N Mahajan
2012-04-16 19:21 ` Randy Dunlap
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